The present invention relates generally to disc drives. More particularly, the present invention relates to an improved ramp for parking read/write heads.
In ramp load disc drives, the head gimbal assembly (HGA) is parked on a ramp when the disc drive is not in operation, instead of being parked directly on the surface of the disc. The HGA needs to be kept on the ramp so that it will not accidentally unload onto the disc. If the ramp is located at the circumference of the disc, the HGA also needs to be kept from accidentally moving off the ramp away from the disc. This can sometimes be achieved by having a notch or an indent on the ramp, as shown in the U.S. Pat. No. 5,875,072 issued Feb. 23, 1999, to Brooks, Jr., et al for xe2x80x9cLow profile head suspension assembly with load and unload capabilityxe2x80x9d and in the U.S. Pat. No. 5,237,472 issued Aug. 17, 1993 to Morehouse et al. for xe2x80x9cRigid disc drive with dynamic head loading apparatusxe2x80x9d. There are, however, situations in which shallow notches may not be sufficient to keep the HGAs from moving off the ramp away from the disc.
For example, some disc drives designs include a latch for keeping the HGA from loading onto the disc when the disc drive is not in operation. The strength of the latch may vary from one disc drive to another, owing to variations in manufacturing tolerances. In some cases, the latch may be too strong and tend to pull the HGA off the ramp away from the disc. When the actuator is depopulated, that is when the read/write heads are removed from the actuator, and its mass is decreased, a similar problem surfaces, even with latches which are of the desired strength for a populated actuator. Such problems cannot be easily solved by decreasing the strength of the latch since that will increase the likelihood of the HGA moving off the ramp in the opposite direction to hit against the disc, thereby resulting in possibly irreparable damage.
The U.S. Pat. No. 5,742,453 entitled xe2x80x9cPassive non-contact magnetic latch for an actuator of a disc drivexe2x80x9d issued Apr. 21, 1998 to Macpherson describes a latch the strength of which is less dependable on manufacturing tolerances and may be used even in cases where the actuator is depopulated. However, this involves the use of an outer-diameter (OD) crash-stop to prevent the HGA from moving off the ramp by limiting the extent of rotation of the actuator as the latch will tend to pull the HGA off the ramp away from the disc. Therefore, during the manufacturing process, after the actuator has been installed and before the OD crash-stop is installed, there remains a need for an improved way of keeping the HGA on the ramp.
The present invention provides a solution to this and other problems, and offers other advantages over the prior art.
The present invention provides for an improved ramp such that the head gimbal assemblies (HGAs) are prevented from moving off the ramp away from the discs. In a preferred embodiment, a ramp has a surface against which a load beam of a HGA rests when the HGA is in the unloaded position. The surface includes a sharp detent configured for retaining the load beam and thus preventing the load beam from sliding off the surface.
In one embodiment, the surface includes a concave, depressed or indented portion ending in a generally vertical wall as it approaches the distal end of the ramp tooth. The distal end of the ramp tooth being the end that is designed to be further away from the disc when the ramp is assembled at the outer edge of a disc in a disc drive.
Alternatively, a top surface of a ramp tooth includes a slope leading down and towards the distal end to terminate in a generally vertical wall. In yet another embodiment, the top surface of a ramp tooth includes a step between the proximal portion of the top surface and a distal portion of the top surface such that the distal portion of the top surface is at a higher elevation that the proximal portion of the top surface.
These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.